My first adaptation on the earth oven was to add a metal chimney with an air vent on the bottom.
Well, I finally felt the old thing was getting to a point that it needed some serious repair, and quite possibly to be torn down and rebuilt. As I started digging in, I decided that I'd just re-do the doorway. Here it is with all the bad stuff removed:
Shots of first round of extra cob for a new archway door and official chimney hole.
Lucky for me I had help!
Add a few tiles, a bit of earthen plaster, and fire it up!